1. Field of the Invention
The present invention relates to a camera with a self-contained flash unit.
2. Description of the Related Art
Conventional camera mechanisms for positioning a self-contained flash unit at stored and popped-up positions and for moving the flash unit between these two positions comprise a combination of a spring and a clamping device. Such positioning and moving mechanisms are disclosed in, for example, Japanese Utility Model Laid-Open No. 127534/1987. FIGS. 3 (a) and 3 (b) respectively show the above-described conventional mechanism in the states where the flash unit is disposed in stored and popped-up positions. In FIGS. 3 (a) and 3 (b), reference numeral 1 denotes a camera body shown in outline. Although the camera body 1 practically comprises a cover member that determines the external appearance of the camera body, only the outline thereof is shown in FIGS. 3 (a) and 3 (b) to simplify the illustration. Reference numeral 2 denotes a flash unit which is movable between the stored and popped-up positions. The flash unit 2 includes a housing 3 which is rotatably supported by a fixed shaft 4, and is fixed to the camera body 1, a xenon tube 5 provides a flash light, a reflector 6 supports the xenon tube 5 and reflects the flash light of the xenon tube 5 toward an object located in front of the camera, a transparent panel 7 transmits the flash light, and is fixed to the housing 3 for supporting the reflector 6, and a torsion coil spring 8 is mounted on the fixed shaft 4. One end of the spring 8 is hooked onto the fixed shaft 4 while the other end thereof is hooked onto a protrusion 3e of the housing 3. The spring 8 biases the housing 3 in a clockwise direction. A fan-shaped hole 3a, centered on the fixed shaft 4, is formed in the housing 3. A protrusion 9, formed integrally with the camera body 1, is fitted into the hole 3a. A protrusion 3d, which will be described in detail later, is provided in the housing 3 for locking the casing at its stored position.
A clamping lever 10 is rotatably supported on the camera body 1 by a pin 10a. The clamping lever 10 has, at one end, a claw portion 10b which engages the protrusion 3d of the housing 3 and at the other end an extending portion 10c which engages an operation button 11 protruding from the camera body 1. The clamping lever 10 is biased by a spring (not shown) in a counterclockwise direction.
Consequently, in the state shown in FIG. 3 (a), the claw portion 10b engages the protrusion 3d of the housing 3 and thus holds the housing 3 at the position shown in FIG. 3 (a) against the bias force of the spring 8 while the extending portion 10c pushes up the operation button 11.
When the camera user desires to take pictures using the flash unit, he or she depresses the operation button 11. Depressing the operation button 11 rotates the clamping lever 10 clockwise against the spring (not shown), and thereby disengages the claw portion 10b from the protrusion 3d of the housing 3. Consequently, the housing 3 rotates clockwise about the fixed shaft 4 due to the bias force of the spring 8 until one end portion 3b of the fan-shaped hole 3a of the housing 3 comes into contact with the protrusion 9 and then stops, thereby providing the state shown in FIG. 3 (b). At that time, a switch (not shown) generates a signal which begins the preparation for a picture taking operation using the flash unit, e.g., initiating the charging of the flash unit capacitor (not shown).
When the camera user manually rotates the flash unit 2 counterclockwise against the bias force of the spring 8 from the state shown in FIG. 3 (b), the claw portion 10b of the clamping lever 10 once again comes into engagement with the protrusion 3d of the housing 3, and is returned to the state shown in FIG. 3 (a).
However, the above-described conventional mechanism which uses a clamping lever to hold the flash unit at the stored state has the following drawbacks.
To ensure that the claw portion 10b of the clamping lever 10 reliably engages the protrusion 3d of the housing 3, the flash unit 2 must be rotated slightly further counterclockwise from the state shown in FIG. 3 (a). This further rotation is necessary to compensate for dimensional tolerances present in the clamping mechanism, and is achieved by providing a gap "X" between the flash unit 2 and the camera body 1, as shown in FIG. 3 (a). However, if the gap "X" is large, spring backlash will be present which allows the flash unit 2 to move when it is pressed, which deteriorates the quality and finish of the camera.
Since the claw portion 10b of the clamping lever 10 is located between the camera body 1 and the flash unit 2, the width of the camera body 1 is increased as viewed, for example, from the left in FIG. 3, which increases the overall size of the camera.
Furthermore, the switch is generally changed over synchronously with the movement of the flash unit 2 to its popped-up position to generate a change-over signal which begins the preparation for a picture taking operation using the flash unit 2. Naturally, the biasing force of the spring 8 gradually weakens as the number of times the flash unit 2 moves to its popped-up position increases.
Therefore, the biasing force of the spring 8 must be strong enough to change over the switch and to bias the flash unit 2 to its popped-up position.
However, to increase the spring bias force, it is necessary to increase the diameter of the spring wire and/or the number of burns of the spring 8, which increases the size of the spring 8. This, in turn, increases the overall size of the camera, and requires a larger amount of operating force to be applied to the operation button 11 to disengage the clamping lever 10.